Brief summaries of tropical Atlantic activity tailored to the general public, coastal residents, and weather enthusiasts. I have been sending out these updates since 1996, and appreciate everyone's continued interest!

04 September 2011

Katia rapidly intensifies, Lee makes landfall

Not much changed since my last update on Friday... Katia has been hovering on the 60-65kt mark, which also means switching between TS and hurricane each time (fairly big name shift for a very minor change in wind speed). The vertical shear has been much slower to let up than forecast (except for the GFDL model, which did see this extended period of high shear, but it was an outlier), and as a result, Katia did not intensify as forecast... but also didn't weaken much either. However, conditions have improved over the past few hours, and the storm was quick to respond in a big way. The intensisty as of 15Z today has skyrocketed up to 85kts with a central pressure of 966mb, and a open, clear eye is forming... it was a 60kt TS with a pressure of 992mb six hours ago! The center is about 375 miles northeast of the northern Leeward Islands. The forecast is still for additional intensification, and for a continued northwest track; it's looking quite likely now that Katia will recurve prior to reaching the US east coast, AND stay to the west of Bermuda.

Shortly after my update on Friday, TD13 was upgraded to TS Lee based on aircraft recon. Since then, it did not intensify much, but as expected, remained a large amorphous rainmaker, crawling along at 2-5kts. It made landfall about 50 miles west of Morgan City with 40kt sustained winds. But more importantly, the rain keeps falling.

There has already been up to a foot of rain across the southern coast,
from LA to AL, over the last 3 days.
More will come today and tomorrow. Lee should still be over southern LA for at least another day, then begin
accelerating to the northeast ahead of a mid-latitude trough...
tracking over MS, AL, and TN over the next 3-4 days. The graphic below shows the estimated rainfall totals over the past 4 days in the region:

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Author: Brian McNoldy,Senior Research Associate at University of Miami's Rosenstiel School of Marine and Atmospheric Science

"In the eye of a hurricane, you learn things other than of a scientific nature. You feel the puniness of man and his works. If a true definition of humility is ever written, it might well be written in the eye of a hurricane." -Edward Murrow, reporting on Hurricane Edna 1954